Bilium is a planet in the FS-176 system. Its only mention was in the Space Pirate Observatory in Metroid Prime. A notable feature of the planet is that it is the closest planet to its star, FS-176. It is one of three known objects in the system to have a retrograde orbit, however it has a normal rotation. Otherwise, it has one of the most stable orbits and does not approach or cross paths with other planets like the rest in the system do. It is very close to a large asteroid field that encloses it in with its sun.